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[Article] A Comparative Review of the Methodologies to Identify a Global
Earthing System
Original Citation:
Colella, Pietro; Pons, Enrico; Tommasini, Riccardo (2017). A Comparative Review of the
Methodologies to Identify a Global Earthing System. In: IEEE TRANSACTIONS ON INDUSTRY
APPLICATIONS, vol. 53 n. 4, pp. 3260-3267. - ISSN 0093-9994
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DOI:10.1109/TIA.2017.2680399
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A Comparative Review of the Methodologies to
Identify a Global Earthing System
Pietro Colella, Member, IEEE Enrico Pons, Member, IEEE and Riccardo Tommasini, Member, IEEE
Dipartimento Energia
Politecnico di Torino
Torino, 10129, Italy
Email: pietro.colella@polito.it
Abstract—International Standards IEC 61936-1 and EN 50522
define a Global Earthing System (GES) as the earthing network,
created by the interconnection of local earthing systems, that
should guarantee the absence of dangerous touch voltages.
Despite that, Standards do not provide any official practical
guidelines for its identification. The official classification of GES
areas would lead to a simplification of the design and verification
procedures of MV/LV substations grounding systems, with associated economical savings for both Distribution System Operators
(DSOs) and MV users. To overcome this regulatory vacuum,
several teams of researchers proposed methods to identify the
presence of a GES.
In this paper, the main methods developed to identify a GES
are presented. The different methodologies are applied to a real
urban scenario and compared.
Index Terms—Electrical safety, global earthing system, grounding, identification method, indirect contacts, MV distribution
system, power distribution faults, power system faults.
I. I NTRODUCTION
The international and European standards IEC 61936-1 [1]
and EN 50522 [2] define a Global Earthing System (GES) as
an “equivalent earthing system created by the interconnection
of local Earthing Systems (ESs) that ensures, by the proximity
of the earthing systems, that there are no dangerous touch
voltages”. The same standards explain that “Such systems
permit the division of the earth fault current in a way that
results in a reduction of the earth potential rise (EPR) at the
local earthing system. Such a system could be said to form a
quasi-equipotential surface” and that “the existence of a global
earthing system may be determined by sample measurements
or calculations for typical systems. Typical examples of global
earthing systems are in city centers, and urban or industrial
areas with distributed low- and high-voltage earthing”.
In the definition, three important concepts are expressed:
interconnection, proximity and quasi-equipotentiality [3], [4].
From a practical point of view, it can be said that GES has
two main effects:
• a fault current distribution among the interconnected ESs;
• a smoothing of the ground potential profile, so that no
dangerous touch voltages occur.
This paper was developed as part of the research “METERGLOB” cofunded by the CCSE (today CSEA, Cassa per i Servizi Energetici e Ambientali) with the participation of six partners: Enel Distribuzione, Istituto
Italiano del Marchio di Qualitá IMQ, Politecnico di Bari, Politecnico di
Torino, Universitá di Palermo and Sapienza Universitá di Roma.
In the last decades, several experiments were carried out to
a better comprehension of these phenomena.
In particular, about the first effect, an analytical model that
computes current distribution among the interconnected ESs
was developed and applied to different test cases. According
to the simulation results, the main factors which influence
the fault current distribution are the presence of bare buried
conductors, the presence of LV neutral conductors, the per
unit length resistance of the cables sheaths and the number of
interconnected MV/LV substations [5], [6], [7], [8].
Moreover, currents measurements were conducted during
a real MV single line to ground fault (SLGF) to evaluate the
effects of the ESs interconnection by experience [9], [10], [11],
[12], [13].
Another important factor, which should always be considered, is the connection of the MV cables sheaths to the groundgrid of the HV/MV substation; in fact, besides modifying the
MV fault current distribution, this interconnection can produce
dangerous touch voltages in the MV grid when a fault on the
HV network occurs as well [14], [15].
Similarly, for the evaluation of the second effect produced
by a GES, field measurements were carried out to characterize
the different types of extraneous conductive parts (such as, for
example, water and gas pipes) that can be buried in urban areas
[16], [17], [18]; the effects of these parts on the ground potential profile were analyzed by an analytical model, based on the
Maxwell’s subareas method [19]. According to the simulation
results, a significant smoothing of the ground potential profile
occurs only if buried conductors are widespread and connected
to the MV grounding network. If metallic parts are widespread
but not interconnected with grounding systems, their effect is
negligible. An example of important contribution is provided
by distributed LV neutral grounding [20], [21], [22].
However, even if the physical phenomena related to the GES
definition are now almost clear, no official practical guidelines
are given in any standard yet. The main problem is that it is
quite simple to evaluate the behavior of a specific system,
while it is difficult to produce general guidelines, valid in all
the possible different situations, based on simple rules easy to
verify, as shown in a previous work of the Authors’ [23].
The identification and official classification of GES areas
would lead to a simplification of the design and verification
procedures of MV/LV substations grounding systems, with
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associated economical savings for both Distribution System
Operators (DSOs) and MV users. In fact, according to EN
50522, if an ES become a part of a GES, no field measurement
to determine soil characteristics, EPRs or touch voltages is
required [2].
In this paper, the main methods that have been developed
in order to identify a GES are presented. Strengths and weaknesses are emphasized. When possible, the methodologies are
applied to a real urban scenario, potentially candidate to be
defined as a portion of GES. Moreover, to better evaluate the
accuracy of the methods, the maximum EPR for each of the
considered MV/LV substations was computed by a dedicate
software and used to evaluate if dangerous voltages can appear
in case of SLGF.
II. M ETHODS TO IDENTIFY A GES
A. Ellipse Method
This methodology was developed by the main Italian DSO,
Enel Distribuzione S.p.A. (now e-distribuzione), and consists
of 6 steps [24], [25]:
1) given a geographical map of the urban area under
investigation, a circle with radius equal to 150 m is
drawn at the center of each MV/LV substation;
2) an ellipse characterized by a major and minor axis of
respectively 1000 m and 500 m is superimposed;
3) if 10 MV/LV substations are included by the ellipse and
interconnected according to the in-out scheme, they are
selected;
4) for the selected group, the tangent lines to the circles
of the more peripheral MV/LV substations are drawn.
In this way, an area with a density of about 25 MV/LV
substations for km2 can be defined;
5) the position of the ellipse is varied and the previous steps
are repeated;
6) the union of the adjacent areas and of the ESs immediately outside its edge (far less than a quarter of the
minimum diagonal of the area) forms a GES.
The ellipse method is based on the DSO’s practical knowledge and takes into account only the density of MV/LV
substations (DS ) in a geographical area. No rationale was
provided to justify the method. Other factors that significantly
influence the two GES effects (i.e. distribution of the fault
current and equipotentialization of the area), such as the
effective cable length between two consecutive substations,
the sheath resistance per unit length or the resistance to earth
(RE ) of the ESs, are neglected [6].
B. Desmedt Method
A Belgian team proposed an interesting methodology to
assess the presence of a GES in a distribution system with
low impedance neutral earthing [26], [27].
According to this method, a necessary but not sufficient
condition is that at least 20 ESs have to be interconnected
through the MV cable shields and/or other protective conductors. In addition, to certify the presence of a GES, at least one
of the following conditions shall also be verified:
IB
IRS
RES
UE • UvT • UT
IB
ZT
RF = RF1 + RF2
UvTp
RF1
UT
UvT
UE = RES x IRS
RF2
Figure 1. Increment of the permissible EPR (UE ) due to the earth surface
potential profile and additional resistances. IB is the current flowing through
the human body, ZT is the total body impedance, RF 1 is the resistance of
the footwear, RF 2 is the resistance to earth of the standing point.
1) the cable lengths, in m, are not greater then LM ax (1);
2) at least 1 km of cables with earthing effect is involved
and the mean length of each part of cable without
earthing effect does not exceed LM ax (1).
Where the maximum length LM ax is to be computed by
means of equation (1):
LM ax ≤ 500 ·
Sm
16 (mm2 )
(1)
where Sm is the weighted average cross-sectional area of
the protective conductors, in mm2 .
In the methodology development, the maximum permissible
EPR is considered twice the value of the permissible touch
voltage as suggested by EN 50522 [2]. In fact, as shown in
Fig. 1, the prospective touch voltage is just a portion of the
EPR. Moreover, additional resistances were taken into account
to determine the prospective permissible touch voltage UvT p ,
according to EN 50522 (Annex B) [2]. As shown in Fig. 1,
the resistance of the footwear RF 1 and the resistance to earth
of the standing point RF 2 are in series with the total body
impedance ZT .
An extensive research activity is at the root of the proposed
formulation, which allows a fast and simple evaluation. These
qualities are probably the main strenghts of the Desmedt
method.
Vice-versa, the weakness is that this method cannot be used
for systems with a different neutral earthing type.
C. Fickert Method
This method was proposed by an Austrian research team
and it is based on the results of touch and step voltages
measurements campaigns [28].
The tests were carried out in different scenarios. In particular, a substation and two MV overhead line terminal towers
were selected in a rural area; furthermore, the measurements
were repeated inside and outside a small village.
The maximum values of the ratio between the measured
touch voltages and the fault current are reported in Table I.
Among the considered cases, very small touch voltages were
found in any of the scenarios, with the only exception of the
measurements in the MV overhead line terminal towers.
Table I
R ATIOS BETWEEN THE MAXIMUM TOUCH VOLTAGES AND THE FAULT
CURRENT.
Scenario
Rural area / substation
Rural area / MV overhead terminal towers
Small village / center
Small village / suburb
ZES
D. Campoccia Method
A research team affiliated with the University of Palermo
(Italy) proposed simplified circuital models to compute the
EPR for 3 fault events: SLGF, Double Ground Fault (DGF)
and SLGF on the HV side of the HV/MV station [29].
The models are approximated but it can be proved that the
errors are not significant if the following conditions are met:
1) the resistance to earth RE of MV/LV substation ESs can
be considered the same;
2) the distance between two consecutive substation is approximately equal;
3) the presence of metallic elements interconnecting the
earth electrodes of the substations but not under the
control of the distribution companies (like water and gas
lines) can be neglected;
4) the earth resistances of all the earth electrodes of the LV
installations, even if connected to the earth electrodes of
the substations included in the GES can be neglected.
For the sake of brevity, only the SLGF case is reported here.
With reference to the electrical circuit of Fig. 2, the EPR of
the faulted substation can be computed from eq. (2).
a
b
· ZE,H
RE · ZE,H
a
b
a
b
RE · ZE,H
+ RE · ZE,H
+ ZE,H
· ZE,H
where:
• IF 1 is the SLGF current;
ZS
ZS
ZS
IF1
[V/kA]
14
700
10
90
One of the main conclusions of the paper is that GESs
shall have an equivalent earthing impedance below 10 mΩ,
considered as the ratio between the touch voltage and the earth
fault current. In other words, for each kA of fault current, the
touch voltage increase by 10 V.
Taking 80 V as the maximum permissible touch voltage
(as suggested by EN 50522 when the duration of current
flow is longer than 10 s), and considering the GES equivalent
earthing impedance cited above, the Authors suggest 8 kA as
the maximum value of the SLGF current that guarantees that
the permissible touch voltage limit is respected [2]. However,
they recommend to carry out real current injection tests for
typical and critical fault locations in order to classify a given
grounding situation.
According with the Authors, also small villages can potentially be defined as a GES.
The fragility of the method seems to be in the low number
of the carried out measurements. In fact it is not clear if the
sample investigated can be considered representative.
UE,H =
ZS
· IF 1 (2)
RE
RE
RE
RE
Figure 2. SLGF circuit model. The impedance ZES is the earth impedance
of the HV/MV station; RE is the average value of the MV/LV substation
earth impedance; ZS is the average value of the metal sheaths impedance.
•
•
RE is the earth resistance of each MV/LV substations;
b
a
ZE,H
and ZE,H
are the driving-point impedances of the
metal sheaths calculated according to [30].
Once the EPRs are computed thanks to the simplified
models, according to the Authors it is possible evaluate the
“Global Safety” of the interconnected ESs. A GES can be
certified if the minimum requirements for interconnection of
LV and HV ESs with regards to indirect contact (CENELEC
HD 637 S1) are fulfilled [29] for all the considered fault types.
The results of the calculation provide useful indications on
the behavior of GES in different fault conditions and can be
used to investigate on which elements can have influence on
Global Safety.
The more the conditions described above are met, the
better the model works. However, real MV networks are quite
complex systems and it is not guaranteed that the assumptions
can always be accepted.
E. Parise Method
Another Italian team affiliated with the University of Roma
“La Sapienza” proposed a method based on field measurements [31]. In particular, touch and step voltages measurements with auxiliary current electrodes at reduced distance
are required [32], [33], [34].
This test can be a valid tool to evaluate the efficacy of ESs in
high densely populated areas or in cases where the extension
of the ES is large. In fact, in these areas, the evaluation of
the EPR for the observance of the permissible touch voltage
is not simple. According to the Fall-of-potential method given
in the international standard EN 50522 (Annex L) [2], the
distances between the voltage probe and the earth electrode
under test must be at least 4 times the maximum dimension.
In practical cases, it is quite difficult to fulfill this condition.
The auxiliary current electrodes method allows a conservative
evaluation of the touch voltage. The higher is the number of
auxiliary electrodes, the lower is the error of the measures
[32].
The Authors assert that this method can be adopted to
identify a GES as well: in a GES, the touch/step voltages
measurements do not significantly change if one or more
auxiliary current electrodes are adopted [31].
The weakness of the method lies in its potentially being
time and money consuming. If adopted, extensive field mea-
Table II
T YPICAL CHARACTERISTICS OF THE MOST COMMON MV CABLES IN THE
NETWORK .
Quantity per unit lenght
phase resistance [Ω/km]
sheath resistance [Ω/km]
phase - sheath capacitance [μF/km]
usage in the network [%]
Cross section [mm2 ]
95
150
185
0.320
1.15
0.238
8
0.206
0.73
0.277
61
0.164
0.73
0.300
26
surement should be carried out and the GES benefit would be
scaled down.
III. M ETHODS APPLICATION AND COMPARISON
The methods described in the previous section are here
applied to the feeder of a real urban network reported in Fig.
3. For confidentiality issues, any geographical references and
labels were deleted.
The grid rated voltage is 22 kV. The system is operated with
isolated neutral and the SLGF current computed by the DSO
is 284 A. The permissible touch voltage UT P is 220 V.
A disconnector keeps the phases interrupted (not the cables
sheaths, which are never interrupted) in one of the substations,
making the meshed system a radially operating network.
Each MV/LV substation is interconnected to the MV lines
according to the in-out insertion scheme.
Fig. 4 reports the distribution of the cable length with
respect to the average value.
The considered network is almost totally composed of underground cable lines. The characteristics of the most common
cables used in the MV system (covering globally 95% of the
network) are reported in Table II. In the selected MV line,
only 185 mm2 cables are used.
For all the MV/LV substation, ESs are formed by a grounding ring buried at 0.75 m from the soil surface. The local
Resistances to Earth (RE s) are not available and therefore a
typical value of 5 Ω was considered for all the ESs.
No bare conductors were buried together with the power
cables; the interconnection among the ESs of the MV/LV
substations is made by MV cable sheaths only.
To limit the problem of exported dangerous voltages in case
of SLGF on the HV side, an insulating joint between the MV
cable sheaths and the earthing system of the HV/MV station
is placed.
In each of the following subsections, one of the methods
for the identification of GESs is applied with the exception
of “Parise Method”, which cannot be tested because measurements are required.
To estimate the accuracy of the methods, a SLGF was
simulated in each MV/LV substation of the system by a
dedicated software (from this point on “reference model”)
[6]. For each of the MV/LV substations, the maximum EPR,
EP RM ax , among the different simulations was evaluated,
varying the position of the SLGF (Fig. 5, green line with circle
Figure 3. Comparison among the methods: the considered MV line.
900
800
700
600
[m]
500
400
300
200
100
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Substationname:cablefirstend
Cablelenght
Cablelenghtaverage
Figure 4. Campoccia method: distribution of the cable length with respect to
average value.
250
200
[V]
150
100
This result partially disagrees with the suggestions obtained
by the reference model. As shown in Fig. 5, the computed EPR
(green line with circle markers) is smaller than UT p (red line)
for all the considered substations, which therefore have rights
to become part of a GES. However, it is important to highlight that the excluded MV/LV substations are the ones that
present the higher EPRs. This proves that density of MV/LV
substations in a geographical area is an important parameter,
even if others factors should be taken into account. In fact,
if the substations 1-6 present quite high EPRs, substation 25
does not have particular issues that prevent its inclusion into
a GES.
The main critical point of this method is the fact that a great
importance is given to the geographical layout of the MV/LV
substations. In fact, if MV/LV substations were arranged in a
different layout, the MV network characteristics being equal
(same cable lengths, etc.), the results obtained from the ellipse
method would be completely different. However, this difference cannot be justified considering that the influence of a
typical MV/LV substation ES is significant only within 4 times
its maximum extension (i.e. about 40 m if it is considered
isolated [2]). Therefore, even if the MV/LV substations were
closer to the GES area, significant modification of the ground
potential profile would not be necessarily obtained.
B. Desmedt Method
50
0
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
MV/LV substation name
Reference values
Campoccia Method
U
UTp
Figure 5. Comparison between the permissible touch voltages and the
maximum EPRs computed by both the reference model and Campoccia
method for the considered case study.
markers). Considering UT p as safety threshold, it was assumed
that a MV/LV substation can be part of a GES if condition
(3) is verified:
EP RM ax < UT p
(3)
Notice that condition (3) is stricter than the requirement
provided by Condition C2 of EN 505221 . This was an authors’
choice, for the sake of safety.
A. Ellipse Method
The circles and ellipses required by the method are superimposed to the plan view of the considered MV line, Fig. 6. In
the same figure, on the right, the GES resulting by the method
is emphasized by the blue hatch.
According to this method, several MV/LV substations
(25/31) could be declared part of a GES. The remaining
substations are instead not included in the GES because their
density is lower than the minimum required.
1 EN 50522, section 5.4.2, condition C2: “permissible values are considered
to be satisfied if the earth potential rise, determined by measurement or
calculation does not exceed double the value of the permissible touch voltage.
This method was developed for a system with lowimpedance neutral earthing [26]. However, it was applied to
the studied scenario as well.
As the number of interconnected substations is 31 (the
minimum requirement is 30) and the condition of eq. (1) is
fulfilled (LM ax = 781 m), all the considered ESs can be
declared GES, in accordance with the suggestion provided by
the reference model.
Due to its simplicity and speed, this method should be
adopted as reference.
C. Fickert Method
According to the Authors, the maximum fault current value
that verifies the observation of the permissible touch voltage is
8 kA, which is greater than the SLGF current computed by the
DSO (i.e. 284 A). Consequently, according to this method, all
the substations form a GES, in accordance with the indication
provided by the reference model.
D. Campoccia Method
The Authors of this method proposed three simplified circuit
models in order to consider the main fault current events. Here,
for the sake of brevity, only the SLGF case analysis is carried
out.
The method allows to compute the EPR by the calculation of
the driving-point impedances of the metal sheaths, on the base
of the formulas reported in [30]. Since these were developed
considering a finite chain without branches, it was necessary
to make some approximations to use it in a real MV network,
which is weakly meshed and where laterals are present.
Figure 6. Ellipse method: an application example.
Moreover, since these formulas require the interconnection
between the MV cable sheath and the ES of the HV/MV
substation, which is not present in the considered case study,
the EPR for the first MV/LV substation (number 2) could not
be calculated.
and its average value is shown in Fig. 4. Although a certain
variability can be noticed, it is not possible to stipulate apriori if the requirement is met. In fact, no details about the
variability that keeps the error under an acceptable threshold
are given.
Among the conditions that should be verified to use the
method without a significant error, the first two are probably
the most stringent: the RE of MV/LV substation ESs could be
considered the same; the cable length between two consecutive
substations is approximately equal.
According to the position of the faulted MV/LV substation,
a
b
, ZE,H
the driving-point impedances of the metal sheaths ZE,H
varies in the range 1.1÷2.8 Ω. For the considered fault current
(284 A), a variation of the EPR in the range 135 ÷ 188 V
can be computed by eq. (2).
Even if the RES are not available and a typical value
was assumed, the comparisons between the real cable lengths
In Fig. 5, the comparison between the EPRs calculated
by the Campoccia Method (blu line with square markers)
and the reference model (green line with circle markers) is
reported. Both the models indicate that EPRs are smaller than
UT p and, therefore, that the whole feeder could become part
of a GES. However, two observations shall be done: first,
the EPRs computed by the reference model in substations
3, 4 and 5 is slightly higher than those computed according
to the Campoccia Method; second, far from the HV/MV
substation, the Campoccia Method provides results that seems
too conservative.
In conclusion, even if this method can be useful for a general
evaluation of the MV line aptitude to become part of a GES, it
cannot be used for an accurate computation of the fault current
distribution as it requires just few input parameters. Dangerous
scenarios, characterized for example by anomalous distances
between two consecutive substations, could not be detected.
IV. C ONCLUSION
In this paper, the main methods to identify a GES, proposed
in literature, were presented and applied to a real urban
scenario, possible candidate to be certified as a portion of GES.
The maximum EPR for each of the considered MV/LV
substations was computed by a dedicate software and used to
evaluate if dangerous voltages can appear in case of SLGF.
In this way, the accuracy of the methods can be better
appreciated.
Three of the four tested methods certified the presence of
a GES for all the considered area, in accordance with the
results of the reference software. The Ellipse method however
reveals a GES only in the urban districts where the MV/LV
substations density is higher. This result is in contrast with the
output of the simulations. Even if the excluded substations are
mainly the ones that present higher EPRs, these values were
not critical.
Each of the methods have some critical points:
• the Ellipse method gives a great importance to the geographical layout of the MV/LV substations. It does not
seem to be justifiable, especially as the characteristics
of the network (cable properties and lengths, RE of the
MV/LV substations, meshes and interconnections, etc.)
are instead not considered at all. Moreover, it seems to
be too conservative;
• the Desmedt method is particularly interesting even if it
cannot be applied in Italian MV networks, characterized
by isolated neutral or resonant earthing. In fact, it was
designed for a system with-low impedance neutral earthing;
• the Fickert method is particularly fast only if touch voltage measurements should not be carried out. However,
the sample size of touch and step voltage measurements
collected by the Authors seems to be not sufficiently
numerous to produce a general methodology;
• the Campoccia method is interesting for a general evaluation of the MV line aptitude to become part of a GES;
however, it is possible that dangerous scenarios could
not be detected. It cannot provide an accurate analysis
of the fault current distribution. In fact, the MV earthing
•
network is modeled with only an input value for the distance between two consecutive substations and for the RE
of the ESs. Non homogeneous cases cannot be properly
modeled. Moreover, with this method, it is not possible
to take into account weakly meshed configurations and
laterals, as well as the absence of interconnection with
the ES of the HV/MV substation. These aspects caused
same problems in the straightforward application to the
case study;
the Parise method, based on touch and step voltages
measurements with auxiliary current electrodes, allows a
conservative evaluation of the GES safety. Nevertheless,
the weakness of the method lies in its potentially being
time and money consuming. If adopted, extensive field
measurements should be carried out and the GES benefit
would be scaled down.
None of the available methodologies have been massively
adopted by the Italian DSOs. In fact, in Italy, just few cases
of GES are certified. Starting from the main effects of a GES,
an innovative approach that goes beyond the limits of the
presented methods could be an important step-forward for the
GES diffusion.
R EFERENCES
[1] Power installations exceeding 1 kV a.c., Part 1: Common rules. IEC
EN 61936-1, 07 2011.
[2] Earthing of power installations exceeding 1 kV a.c. CEI EN 50522,
07 2011.
[3] G. Cafaro, P. Montegiglio, F. Torelli, P. Colella, R. Napoli, E. Pons,
R. Tommasini, A. De Simone, E. Morozova, G. Valtorta, A. Barresi,
F. Tummolillo, A. Campoccia, M. L. Di Silvestre, E. Riva Sanseverino,
G. Zizzo, L. Martirano, G. Parise, and L. Parise, “The global grounding
system: Definitions and guidelines,” in 2015 IEEE 15th International
Conference on Environment and Electrical Engineering (EEEIC). IEEE,
June 2015, pp. 537–541.
[4] G. Parise, L. Parise, and L. Martirano, “Single grounding system
intrinsically safe and global grounding system safe as set,” in 2016
IEEE 16th International Conference on Environment and Electrical
Engineering (EEEIC). IEEE, June 2016, pp. 1–6.
[5] A. Campoccia, E. R. Sanseverino, and G. Zizzo, “Analysis of interconnected earthing systems of MV/LV substations in urban areas,” in
Universities Power Engineering Conference, 2008. UPEC 2008. 43rd
International. IEEE, 2008, pp. 1–5.
[6] E. Pons, P. Colella, R. Napoli, and R. Tommasini, “Impact of MV
ground fault current distribution on global earthing systems,” Industry
Applications, IEEE Transactions on, vol. 51, no. 6, pp. 4961–4968, 2015.
[7] A. Campoccia and G. Zizzo, “A study on the use of bare buried
conductors in an extended interconnection of earthing systems inside
a MV network,” in Electricity Distribution, 2005. CIRED 2005. 18th
International Conference and Exhibition on. IET, 2005, pp. 1–5.
[8] R. Tommasini, R. Pertusio, and S. Toja, “FEM approach to the study
of global earthing systems,” in International Association of Science
and Technology for Development (IASTED), 2003 3rd International
Conference on, 2003, pp. 737–740.
[9] P. Colella, R. Napoli, E. Pons, R. Tommasini, A. Barresi, G. Cafaro,
A. De Simone, M. L. Di Silvestre, L. Martirano, P. Montegiglio,
E. Morozova, G. Parise, L. Parise, E. Riva Sanseverino, F. Torelli,
F. Tummolillo, G. Valtorta, and G. Zizzo, “Current and voltage behaviour
during a fault in a HV/MV system: methods and measurements,” in
Environment and Electrical Engineering (EEEIC), 2015 IEEE 15th
International Conference on. IEEE, June 2015, pp. 404–409.
[10] ——, “Currents distribution during a fault in an MV network: Methods and measurements,” Industry Applications, IEEE Transactions on,
vol. 52, no. 6, pp. 4585–4593, 2016.
[11] M. Lindinger, L. Fickert, E. Schmautzer, and C. Raunig, “Grounding
measurements in urban areas-comparison of low and high voltage
measurements in common grounding systems,” in PowerTech, 2011
IEEE Trondheim. IEEE, 2011, pp. 1–6.
[12] M. J. Lindinger, L. Fickert, E. Schmautzer, and C. Raunig, “Global
earthing systems–verification and limits a comparison of simulations
and measurements.”
[13] P. Toman, J. Dvovrák, J. Orságová, and S. Mivsák, “Experimental
measuring of the earth faults currents in mv compensated networks.”
IET, 2010.
[14] A. Campoccia, L. Mineo, and G. Zizzo, “A method to evaluate voltages
to earth during an earth fault in an HV network in a system of
interconnected earth electrodes of MV/LV substations,” Power Delivery,
IEEE Transactions on, vol. 23, no. 4, pp. 1763–1772, 2008.
[15] M. L. Di Silvestre, L. Dusonchet, S. Mangione, and G. Zizzo, “On
the effects of HV/MV stations on global grounding systems,” in 2016
IEEE 16th International Conference on Environment and Electrical
Engineering (EEEIC). IEEE, 2016, pp. 1–6.
[16] M. Mitolo, M. Tartaglia, and S. Panetta, “Of international terminology
and wiring methods used in the matter of bonding and earthing of lowvoltage power systems,” IEEE Transactions on Industry Applications,
vol. 46, no. 3, pp. 1089–1095, 2010.
[17] G. Cafaro, P. Montegiglio, F. Torelli, P. Colella, E. Pons, R. Tommasini,
and G. Valtorta, “Global earthing systems: Characterization of buried
metallic parts,” in 2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC). IEEE, June 2016, pp.
1–6.
[18] C. Wahl and E. Schmautzer, “Impact of global earthing systems on
the inductive interference on buried isolated metallic pipelines,” in
23nd International Conference on Electricity Distribution, Lyon, France,
2015.
[19] M. Sylos Labini, A. Covitti, G. Delvecchio, and C. Marzano, “A study
for optimizing the number of subareas in the Maxwell’s method,” IEEE
transactions on magnetics, vol. 39, no. 3, pp. 1159–1162, 2003.
[20] E. Pons, P. Colella, R. Tommasini, R. Napoli, P. Montegiglio, G. Cafaro,
and F. Torelli, “Global earthing system: can buried metallic structures
significantly modify the ground potential profile?” Industry Applications,
IEEE Transactions on, vol. 51, no. 6, pp. 5237–5246, 2015.
[21] G. Cafaro, P. Montegiglio, F. Torelli, A. Barresi, P. Colella, A. De Simone, M. L. Di Silvestre, L. Martirano, E. Morozova, R. Napoli,
G. Parise, L. Parise, E. Pons, E. Riva Sanseverino, R. Tommasini,
F. Tummolillo, G. Valtorta, and G. Zizzo, “Influence of LV neutral
grounding on global earthing systems,” in 2015 IEEE 15th International
Conference on Environment and Electrical Engineering (EEEIC), June
2015, pp. 389–394.
[22] ——, “Influence of LV neutral grounding on global earthing systems,”
IEEE Transactions on Industry Applications, vol. PP, no. 99, pp. 1–1,
2016.
[23] P. Colella, E. Pons, and R. Tommasini, “The identification of global
earthing systems: a review and comparison of methodologies,” in 2016
IEEE 16th International Conference on Environment and Electrical
Engineering (EEEIC). IEEE, June 2016, pp. 1–6.
[24] Impianti di terra delle cabine secondarie. Enel Distribuzione DK 4461,
12 2002.
[25] G. Valtorta, “Adeguamento alla norma CEI 11.1 delle prescrizioni enel
distribuzione sugli impianti di terra delle cabine secondarie,” Bollettino
Ingegneri, no. 6, pp. 14–16, 2005.
[26] M. Desmedt, J. Hoeffelman, and D. Halkin, “Use of a global earthing
system to implement the safety requirements for protecting against
indirect contacts in HV systems,” in Electricity Distribution, 2001. Part
1: Contributions. CIRED. 16th International Conference and Exhibition
on (IEE Conf. Publ No. 482), vol. 2. IET, 2001, pp. 10–pp.
[27] M. Desmedt, J. Haeffelman, and D. Halkin, “Utilisation d’un systeme de
mise a la terre globale aux fins de renconter les impositions de protection
contre les contacts indirects en haute tension,” in Electricity Distribution,
2001. Part 1: Contributions. CIRED. 16th International Conference and
Exhibition on (IEE Conf. Publ No. 482), vol. 2. IET, 2001, pp. 16–20.
[28] L. Fickert, E. Schmautzer, C. Raunig, and M. J. Lindinger, “Verification
of global earthing systems,” in Electricity Distribution (CIRED 2013),
22nd International Conference and Exhibition on, 2013, pp. 1–4.
[29] A. Campoccia and G. Zizzo, “Simple circuit models for studying global
earthing systems,” in Power Tech, 2007 IEEE Lausanne. IEEE, 2007,
pp. 1947–1952.
[30] Currents during two separate simultaneous line-to-earth short circuits
and partial short-circuits currents flowing through earth. IEC 60909-3.
[31] G. Parise, L. Parise, and L. Martirano, “Needs of management of
the grounding systems,” Industry Applications, IEEE Transactions on,
vol. 51, no. 6, pp. 5017–5022, 2015.
[32] G. Parise, L. Martirano, L. Parise, S. Celozzi, and R. Araneo, “Simplified
conservative testing method of touch and step voltages by multiple
auxiliary electrodes at reduced distance,” Industry Applications, IEEE
Transactions on, vol. 51, no. 6, pp. 4987–4993, 2015.
[33] G. Parise, L. Parise, and L. Martirano, “Identification of global grounding systems: the global zone of influence,” Industry Applications, IEEE
Transactions on, vol. 51, no. 6, pp. 5044–5049, 2015.
[34] G. Parise, L. Martirano, L. Parise, F. Tummolillo, G. Vagnati, A. Barresi,
G. Cafaro, P. Colella, M. L. Di Silvestre, P. Montegiglio, E. Morozova,
R. Napoli, E. Pons, E. Riva Sanseverino, S. Sassoli, R. Tommasini,
F. Torelli, G. Valtorta, and G. Zizzo, “A practical method to test the
safety of HV/MV substation grounding systems,” in 2015 IEEE 15th
International Conference on Environment and Electrical Engineering
(EEEIC). IEEE, June 2015, pp. 502–506.